The office has served the owner well although it is considerably messier than in the photo. Acoustics have never been a concern in what is, in the most typical circumstances, a two person household. However, diagramming reflection of noises from the living area would support the idea that sound is deflected away from the office.

If the client were to be concerned about lowering living room generated sound levels in the office my suggestion would be to add panels of sound absorbent materials on the walls.

The picture shows a large open volume with mostly hard surface materials (wood, glass, drywall). This makes for a highly reverberant space, and the angles of the roof only serve to make the sound field in the room more DIFFUSE (more even distribution of the sound). Given the existing materials, changes in the shape of the roof would have no perceptible effect in the noise levels you experience in the loft. The best solution would be to add sound absorptive material to the room, mostly at the ceiling. Unfortunately you have a beautiful wood ceiling now that is part of the problem. It would be possible to furr down another wood ceiling using a "slat absorber" design to retain the look and feel of wood, but function acoustically to reduce reverberant sound buildup and reflection into the loft. I suggest you do a google search for "slat absorbers". You should also search for other porous sound absorbent material, such as wall panels, that you could use over the drywall. Use materials/systems that have a NRC (Noise Reduction Coefficient) rating of .7 or more.